This invention relates to pulse-type, peak-power limited radar systems, and particularly to methods and apparatus for frequency-derived pulse compression techniques used in peak-power limited radar systems.
Two methods of reducing cyclic loss of frequency-derived polyphase coded signals due to doppler shift are known in the art. One method requires two channels instead of one, the first of them a standard direct channel, and the second comprising a phase-compensated channel which has approximately a .pi. phase shift across the uncompressed pulse. The channel having the largest signal is then selected. This method is undesirable from the standpoint of cost and complexity associated with the additional phase shifters, channel and signal-selecting circuitry required.
The other known method of reducing cyclic loss due to doppler shift is amplitude weighting of the polyphase-coded signal. The undesirable aspects of this method are the limited degree of reduction in cyclic losses attributable solely to weighting and the reduction in signal-to-noise ratio which results from the general practice of weighting the received polyphase-coded signal.